Wireless terminal architecture is adopting the principles of Software Defined Radio. The main thrust in applying the principles of Software Defined Radio into the handset architecture is to utilize the potential that SDR offers in terms of universal multi-mode terminal functionality within a single reconfigurable platform. This is necessitated by the plethora of standards in Radio Access technologies in both the second and third generation of mobile communication systems. Also, the need to provide true global roaming seamlessly across network boundaries, getting access to services anytime anywhere without having to bother about the underlying technology changes necessitates the terminal to have some amount of reconfigurability built in.
The architecture of a terminal built on the principles on Software Defined Radio follows a distributed computing paradigm. SDR Forum in their Software Communications Architecture Specification, Volume 2.2, suggests CORBA as a middleware. The entire Software Radio is viewed as a heterarchical collection of software components. Each application is viewed as composed of one or more of these components. Adding a new component is termed as commissioning and removing of a component is termed decommissioning of the component. A component can be commissioned, decommissioned or replaced on the fly. The component server is capable of managing the component activity at transaction level granularity.
Over-the-air reconfiguration of wireless terminals provides the true advantages of having a reconfigurable architecture. The terminals can download software components over-the-air and reconfigure the properties of the terminal. Theses components can range from new air interface protocols to new user applications. Some of these components can even change the pattern in the power emission characteristics of the terminal.
The reconfiguration process, as per Architectures Supporting SDR Terminals by Nikolas Olazieregi et al, at the minimum level, requires some generic tasks like available mode lookup, negotiation, over-the-air software download and reconfiguration. Every terminal will have some non-reconfigurable modules that take care of such functionality. The download of software components can be in two ways, namely, user-triggered and system-initiated. User-triggered software downloads can be for user applications such as scheduler, calendar or game applications. System initiated downloads can be for system level components such as CODECs, protocol stack for a new air interface, and modem for a new air interface.
Detection and control of the rogue SDR terminals in the future networks, by Jafar Faroughi-Esfahani et al, describes conditions under which reconfiguration of a terminal could lead to potential problems. The capability of a reconfigurable terminal to download and commission new software components during an operation also throws open the possibility of the terminal malfunctioning and jamming other users in the network.